Chemical compounds

ABSTRACT

Compounds of the general structural formula (I), and use of the compounds and salts and solvates thereof, as therapeutic agents.

FIELD AND BACKGROUND OF THE INVENTION

[0001] This invention relates to a series of compounds, to methods ofpreparing the compounds, to pharmaceutical compositions containing thecompounds, and to their use as therapeutic agents. In particular, theinvention relates to compounds that are potent and selective inhibitorsof cyclic guanosine 3′,5′-monophosphate specific phosphodiesterase(cGMP-specific PDE), in particular PDE5, and have utility in a varietyof therapeutic areas wherein such inhibition is considered beneficial,including the treatment of cardiovascular disorders and erectiledysfunction.

DETAILED DESCRIPTION OF THE INVENTION

[0002] The present invention provides compounds of formula (I)

[0003] wherein R⁰, independently, is selected from the group consistingof halo, C₁₋₆alkyl, C₂₋₆alkenyl, aryl, heteroaryl, C₃₋₈cycloalkyl,C₃₋₈heterocycloalkyl, C₁₋₃alkylenearyl, C₁₋₃alkyleneheteroaryl, Het,C(═O)R^(a), OC(═O)OR^(a), C₁₋₄alkyleneNR^(a)R^(b), C₁₋₄alkyleneHet,C₁₋₄alkyleneC(═O)OR^(a), C(═O)NR^(a)SO₂R^(b), C(═O)C₁₋₄alkyleneHet,C(═O)NR^(a)R^(b), C(═O)NR^(a)C₃₋₄alkyleneOR^(b),C(═O)NR^(a)C₁₋₄alkyleneHet, OR^(a), OC₁₋₄alkyleneC(═O)OR^(a),OC₁₋₄alkyleneNR^(a)R^(b), OC₁₋₄alkyleneHet, OC₁₋₄alkyleneOR^(a),OC₁₋₄alkyleneNR^(a)C(═O)OR^(b), NR^(a)R^(b),NR^(a)C₁₋₄alkyleneNR^(a)R^(b), NR^(a)C(═O)R^(b), NR^(a)C(═O)NR^(a)R^(b),N(SO₂C₁₋₄alkyl)₂, NR^(a)(SO₂C₁₋₄alkyl), nitro, trifluoromethyl,trifluoromethoxy, cyano, SO₂NR^(a)R^(b), SO₂R^(a), SOR^(a), SR^(a), andOSO₂CF₃;

[0004] R¹ is selected from the group consisting of hydrogen, C₁₋₆alkyl,C₂₋₆alkenyl, C₂₋₆alkynyl, haloC₁₋₆alkyl, C₃₋₈cycloalkyl,C₃₋₈cycloalkylC₁₋₃alkyl, arylC₁₋₃alkyl, and heteroarylC₁₋₃alkyl;

[0005] R² is selected from the group consisting of an optionallysubstituted monocyclic aromatic ring selected from the group consistingof benzene, thiophene, furan, and pyridine, and an optionallysubstituted bicyclic ring

[0006] wherein the fused ring A is a 5- or 6-membered ring, saturated orpartially or fully unsaturated, and comprises carbon atoms andoptionally one or two heteroatoms selected from oxygen, sulfur, andnitrogen;

[0007] R³ is hydrogen or C₁₋₆alkyl, or

[0008] R¹ and R³ together form a 3- or 4-membered alkyl or alkenyl chaincomponent of a 5- or 6-membered ring;

[0009] fused ring B is a 5-, 6-, or 7-membered ring, saturated orpartially or fully unsaturated, comprising carbon atoms and optionallyone to three heteroatoms selected from oxygen, sulfur, and nitrogen;

[0010] R^(a) is selected from the group consisting of hydrogen,C₁₋₁₀alkyl, C₂₋₁₀alkenyl, C₂₋₁₀alkynyl, aryl, heteroaryl, arylC₁₋₃alkyl,C₁₋₃alkylenearyl, C(═O)OR^(b), C(═O)N(R^(b))₂, C₁₋₄alkyleneN(R^(b))₂,CF₃, OCF₃, OR^(b), OC(═O)—R^(b), OC₁₋₄alkyleneC(═O)OR^(b),C₁₋₄alkyleneOC₁₋₄alkyleneC(═O)OR^(b), C(═O)NR^(b)SO₂R^(b),C(═O)C₁₋₄alkyleneHet, C₂₋₆alkenyleneN(R^(b))₂,C(═O)NR^(b)C₁₋₄alkyleneOR^(b)C(═O)NR^(b)C₁₋₄alkyleneHet,OC₂₋₄alkyleneN(R^(b))₂, OC₁₋₄alkyleneCH(OR^(b))—CH₂N(R^(b))₂,OC₂₋₄alkyleneOR^(b), OC₂₋₄alkyleneNR^(b)C(═O)OR^(b), N(R^(b))₂,NR^(b)C₁₋₄alkyleneN(R^(b))₂, NR^(b)C(═O)R^(b), NR^(b)C(═O)N(R^(b))₂,N(SO₂C₁₋₄alkyl)₂, NR^(b)(SO₂C₁₋₄alkyl), SO₂N(R^(b))₂,OSO₂trifluoromethyl, C(═O)R^(b), C₁₋₃alkyleneOR^(b), CN, andC₁₋₆alkyleneC(═O)OR^(b);

[0011] R^(b) is selected from the group consisting of hydrogen,C₁₋₆alkyl, aryl, arylC₁₋₃alkyl, C₁₋₃alkylenearyl, heteroaryl,heteroarylC₁₋₃alkyl, and C₁₋₃alkyleneheteroaryl;

[0012] q is 0, 1, 2, 3, or 4; and

[0013] pharmaceutically acceptable salts and hydrates thereof.

[0014] As used herein, the term “alkyll” includes straight chained andbranched hydrocarbon groups containing the indicated number of carbonatoms, typically methyl, ethyl, and straight chain and branched propyland butyl groups. The hydrocarbon group can contain up to 16 carbonatoms. The term “alkyl” includes “bridged alkyl,” i.e., a C₆-C₁₆bicyclic or polycyclic hydrocarbon group, for example, norbornyl,adamantyl, bicyclo[2.2.2]octyl, bicyclo[2.2.1]heptyl,bicyclo[3.2.1]octyl, or decahydronaphthyl. The term “cycloalkyl” isdefined as a cyclic C₃-C₈ hydrocarbon group, e.g., cyclopropyl,cyclobutyl, cyclohexyl, and cyclopentyl.

[0015] The terms “alkenyl” and “alkynyl” are defined identically as“alkyl,” except for containing a carbon-carbon double bond orcarbon-carbon triple bond, respectively. “Cycloalkenyl”, is definedsimilarly to cycloalkyl, except a carbon-carbon double bond is presentin the ring.

[0016] The term “alkylene” refers to an alkyl group having asubstituent. For example, the term “C₁₋₃alkylenearyl” refers to an alkylgroup containing one to three carbon atoms, and substituted with an arylgroup. The term “alkenylene” as used herein is similarly defined, andcontains the indicated number of carbon atoms and a carbon-carbon doublebond, and includes straight chained and branched alkenylene groups, likeethyenylene.

[0017] The term “halo” or “halogen” is defined herein to includefluorine, bromine, chlorine, and iodine.

[0018] The term “haloalkyl”, is defined herein as an alkyl groupsubstituted with one or more halo substituents, independently selectedfrom fluoro, chloro, bromo, and iodo. Similarly, “halocycloalkyl”, isdefined as a cycloalkyl group having one or more halo substituents.

[0019] The term “aryl,” alone or in combination, is defined herein as amonocyclic or polycyclic aromatic group, preferably a monocyclic orbicyclic aromatic group, e.g., phenyl or naphthyl. Unless otherwiseindicated, an “aryl” group can be unsubstituted or substituted, forexample, with one or more, and in particular one to three, halo, alkyl,hydroxyalkyl, alkoxy, alkoxyalkyl, haloalkyl, nitro, amino, alkylamino,acylamino, alkylthio, alkylsulfinyl, and alkylsulfonyl. Exemplary arylgroups include phenyl, naphthyl, tetrahydronaphthyl, 2-chlorophenyl,3-chlorophenyl, 4-chlorophenyl, 2-methylphenyl, 4-methoxyphenyl,3-trifluoromethylphenyl, 4-nitrophenyl, and the like. The terms“arylC₁₋₃alkyl”, and “heteroarylC₁₋₃alkyl” are defined as an aryl orheteroaryl group having a C₁₋₃alkyl substituent.

[0020] The term “heteroaryl” is defined herein as a monocyclic orbicyclic ring system containing one or two aromatic rings and containingat least one nitrogen, oxygen, or sulfur atom in an aromatic ring, andwhich can be unsubstituted or substituted, for example, with one ormore, and in particular one to three, substituents, like halo, alkyl,hydroxy, hydroxyalkyl, alkoxy, alkoxyalkyl, haloalkyl, nitro, amino,alkylamino, acylamino, alkylthio, alkylsulfinyl, and alkylsulfonyl.Examples of heteroaryl groups include thienyl, furyl, pyridyl, oxazolyl,quinolyl, isoquinolyl, indolyl, triazolyl, isothiazolyl, isoxazolyl,imidizolyl, benzothiazolyl, pyrazinyl, pyrimidinyl, thiazolyl, andthiadiazolyl.

[0021] The term “Het” is defined as monocyclic, bicyclic, and tricyclicgroups containing one or more heteroatoms selected from the groupconsisting of oxygen, nitrogen, and sulfur. A “Het” group also cancontain an oxo group (═O) attached to the ring. Nonlimiting examples ofHet groups include 1,3-dioxolane, 2-pyrazoline, pyrazolidine,pyrrolidine, piperazine, a pyrroline, 2H-pyran, 4H-pyran, morpholine,thiopholine, piperidine, 1,4-dithiane, and 1,4-dioxane.

[0022] The term “hydroxyl” is defined as —OH.

[0023] The term “alkoxyl” is defined as —OR, wherein R is alkyl.

[0024] The term “alkoxyalkyl” is defined as an alkyl group wherein ahydrogen atom has been replaced by an alkoxy group. The term“(alkylthio)-alkyl” is defined similarly as alkoxyalkyl, except a sulfuratom, rather than an oxygen atom, is present.

[0025] The term “hydroxyalkyl” is defined as a hydroxy group appended toan alkyl group.

[0026] The term “amino” is defined as —NH₂, and the term “alkylamino” isdefined as —NR₂, wherein at least one R is alkyl and the second R isalkyl or hydrogen.

[0027] The term “acylamino” is defined as RC(═O)N, wherein R is alkyl oraryl.

[0028] The term “alkylthio” is defined as —SR, wherein R is alkyl.

[0029] The term “alkylsulfinyl” is defined as R—SO₂, wherein R is alkyl.

[0030] The term “alkylsulfonyl” is defined as R—SO₃, wherein R is alkyl.

[0031] The term “nitro” is defined as —NO₂.

[0032] The term “trifluoromethyl”, is defined as —CF₃.

[0033] The term “trifluoromethoxyl” is defined as —OCF₃.

[0034] The term “cyano” is defined as —CN.

[0035] Substituents R⁰ can be positioned on a carbon atom or aheteroatom of ring B. In preferred embodiments, q is 0, or R⁰ isselected from the group consisting of C₁₋₆alkyl, aryl, C₁₋₃alkylenearyl,C₁₋₃alkyleneheteroaryl, Het, OR^(a), C(═O)OR^(a),C₁₋₄alkylene-NR^(a)R^(b), C(═O)R^(a), NR^(a)R^(b), C₃₋₈cycloalkyl, andC(═O)NR^(a)R^(b).

[0036] In other preferred embodiments, R¹ is selected from the groupconsisting of hydrogen, C₁₋₆alkyl, haloC₁₋₆alkyl, C₃₋₈cycloalkyl,C₃₋₈cycloalkyleneC₁₋₃alkyl, arylC₂₋₃alkyl, and heteroarylC₁₋₃alkyl.

[0037] In a preferred group of compounds of formula (I), R² isrepresented by

[0038] wherein the bicyclic ring can represent, for example, naphthaleneor indene, or a heterocycle, such as benzoxazole, benzothiazole,benzisoxazole, benzimidazole, quinoline, indole, benzothiophene, orbenzofuran, or

[0039] wherein q is an integer 1 or 2, and G, independently, isC(R^(a))₂, O, S, or NR^(a). The bicyclic ring comprising the R¹substituent typically is attached to the rest of the molecule by aphenyl ring carbon atom.

[0040] In an especially preferred group of compounds of formula (I), R²is represented by an optionally substituted bicyclic ring

[0041] wherein q is 1 or 2, and G, independently, are CH₂ or O.Especially preferred R² substituents include

[0042] Within this particular group of compounds, nonlimiting examplesof substituents for the bicyclic ring include halogen (e.g., chlorine),C₁₋₃alkyl (e.g., methyl, ethyl, or i-propyl), OR^(a) (e.g., methoxy,ethoxy, or hydroxy), CO₂R^(a), halomethyl or halomethoxy (e.g.,trifluoromethyl or trifluoromethoxy), cyano, nitro, and NR^(a)R^(b).

[0043] Examples of ring B include, but are not limited to the following,including residues thereof:

[0044] The R⁰ substituents can be bound to a carbon or a nitrogen atomof the B ring.

[0045] An especially preferred subclass of compounds within the generalscope of formula (I) is represented by compounds of formula (II)

[0046] Compounds of formula (I) can contain one or more asymmetriccenter, and, therefore, can exist as stereoisomers. The presentinvention includes both mixtures and separate individual stereoisomersof the compounds of formula (I). Compounds of formula (I) also can existin tautomeric forms, and the invention includes both mixtures andseparate individual tautomers thereof.

[0047] Pharmaceutically acceptable salts of the compounds of formula (I)can be acid addition salts formed with pharmaceutically acceptableacids. Examples of suitable salts include, but are not limited to, thehydrochloride, hydrobromide, sulfate, bisulfate, phosphate, hydrogenphosphate, acetate, benzoate, succinate, fumarate, maleate, lactate,citrate, tartrate, gluconate, methanesulfonate, benzenesulfonate, andp-toluenesulfonate salts. The compounds of the formula (I) also canprovide pharmaceutically acceptable metal salts, in particular alkalimetal salts and alkaline earth metal salts, with bases. Examples includethe sodium, potassium, magnesium, and calcium salts.

[0048] Compounds of the present invention are potent and selectiveinhibitors of cGMP-specific PDE5. Thus, compounds of formula (I) are ofinterest for use in therapy, specifically for the treatment of a varietyof conditions where selective inhibition of PDE5 is considered to bebeneficial.

[0049] Phosphodiesterases (PDEs) catalyze the hydrolysis of cyclicnucleotides, such as cyclic adenosine monophosphate (cAMP) and cyclicguanosine monophosphate (cGMP). The PDEs have been classified into atleast seven isoenzyme families and are present in many tissues (J. A.Beavo, Physiol. Rev., 75, p. 725 (1995)).

[0050] PDE5 inhibition is a particularly attractive target. A potent andselective inhibitor of PDE5 provides vasodilating, relaxing, anddiuretic effects, all of which are beneficial in the treatment ofvarious disease states. Research in this area has led to several classesof inhibitors based on the cGMP basic structure (E. Sybertz et al.,Expert. Opin. Ther. Pat., 7, p. 631 (1997)).

[0051] The biochemical, physiological, and clinical effects of PDE5inhibitors therefore suggest their utility in a variety of diseasestates in which modulation of smooth muscle, renal, hemostatic,inflammatory, and/or endocrine function is desirable. The compounds offormula (I), therefore, have utility in the treatment of a number ofdisorders, including stable, unstable, and variant (Prinzmetal) angina,hypertension, pulmonary hypertension, congestive heart failure, acuterespiratory distress syndrome, acute and chronic renal failure,atherosclerosis, conditions of reduced blood vessel patency (e.g.,postpercutaneous transluminal coronary or carotid angioplasty, orpost-bypass surgery graft stenosis), peripheral vascular disease,vascular disorders, such as Raynaud's disease, thrombocythemia,inflammatory diseases, stroke, bronchitis, chronic asthma, allergicasthma, allergic rhinitis, glaucoma, osteoporosis, preterm labor, benignprostatic hypertrophy, peptic ulcer, male erectile dysfunction, femalesexual dysfunction, and diseases characterized by disorders of gutmotility (e.g., irritable bowel syndrome).

[0052] An especially important use is the treatment of male erectiledysfunction, which is one form of impotence and is a common medicalproblem. Impotence can be defined as a lack of power, in the male, tocopulate, and can involve an inability to achieve penile erection orejaculation, or both. The incidence of erectile dysfunction increaseswith age, with about 50% of men over the age of 40 suffering from somedegree of erectile dysfunction.

[0053] In addition, a further important use is the treatment of femalearousal disorder. Female arousal disorders are defined as a recurrentinability to attain or maintain an adequate lubrication/swellingresponse of sexual excitement until completion of sexual activity. Thearousal response consists of vasocongestion in the pelvis, vaginallubrication, and expansion and swelling of external genitalia.

[0054] It is envisioned, therefore, that compounds of formula (I) areuseful in the treatment of male erectile dysfunction and female arousaldisorder. Thus, the present invention concerns the use of compounds offormula (I), or a pharmaceutically acceptable salt thereof, or apharmaceutical composition containing either entity, for the manufactureof a medicament for the curative or prophylactic treatment of erectiledysfunction in a male animal and arousal disorder in a female animal,including humans.

[0055] The term “treatment” includes preventing, lowering, stopping, orreversing the progression or severity of the condition or symptoms beingtreated. As such, the term “treatment” includes both medical therapeuticand/or prophylactic administration, as appropriate.

[0056] It also is understood that “a compound of formula (I),” or aphysiologically acceptable salt or solvate thereof, can be administeredas the neat compound, or as a pharmaceutical composition containingeither entity.

[0057] Although compounds of the invention are envisioned primarily forthe treatment of sexual dysfunction in humans, such as male erectiledysfunction and female arousal disorder, they also can be used for thetreatment of other disease states.

[0058] A further aspect of the present invention, therefore, isproviding a compound of formula (I) for use in the treatment of stable,unstable, and variant (Prinzmetal) angina, hypertension, pulmonaryhypertension, chronic obstructive pulmonary disease, congestive heartfailure, acute respiratory distress syndrome, acute and chronic renalfailure, atherosclerosis, conditions of reduced blood vessel patency(e.g., post-PTCA or post-bypass graft stenosis), peripheral vasculardisease, vascular disorders such as Raynaud's disease, thrombocythemia,inflammatory diseases, prophylaxis of myocardial infarction, prophylaxisof stroke, stroke, bronchitis, chronic asthma, allergic asthma, allergicrhinitis, glaucoma, osteoporosis, preterm labor, benign prostatichypertrophy, male and female erectile dysfunction, or diseasescharacterized by disorders of gut motility (e.g., IBS).

[0059] According to another aspect of the present invention, there isprovided the use of a compound of formula (I) for the manufacture of amedicament for the treatment of the above-noted conditions anddisorders.

[0060] In a further aspect, the present invention provides a method oftreating the above-noted conditions and disorders in a human or nonhumananimal body which comprises administering to said body a therapeuticallyeffective amount of a compound of formula (I).

[0061] Compounds of the invention can be administered by any suitableroute, for example by oral, buccal, inhalation, sublingual, rectal,vaginal, transurethral, nasal, topical, percutaneous, i.e., transdermal,or parenteral (including intravenous, intramuscular, subcutaneous, andintracoronary) administration. Parenteral administration can beaccomplished using a needle and syringe, or using a high pressuretechnique, like POWDERJECT™.

[0062] Oral administration of a compound of the invention is thepreferred route. Oral administration is the most convenient and avoidsthe disadvantages associated with other routes of administration. Forpatients suffering from a swallowing disorder or from impairment of drugabsorption after oral administration, the drug can be administeredparenterally, e.g., sublingually or buccally.

[0063] Compounds and pharmaceutical compositions suitable for use in thepresent invention include those wherein the active ingredient isadministered in an effective amount to achieve its intended purpose.More specifically, a “therapeutically effective amount” means an amounteffective to prevent development of, or to alleviate the existingsymptoms of, the subject being treated. Determination of the effectiveamounts is well within the capability of those skilled in the art,especially in light of the detailed disclosure provided herein.

[0064] A “therapeutically effective dose” refers to that amount of thecompound that results in achieving the desired effect. Toxicity andtherapeutic efficacy of such compounds can be determined by standardpharmaceutical procedures in cell cultures or experimental animals,e.g., for determining the LD₅₀ (the dose lethal to 50% of thepopulation) and the ED₅₀ (the dose therapeutically effective in 50% ofthe population). The dose ratio between toxic and therapeutic effects isthe therapeutic index, which is expressed-as the ratio between LD₅₀ andED₅₀. Compounds which exhibit high therapeutic indices are preferred.The data obtained from such data can be used in formulating a dosagerange for use in humans. The dosage of such compounds preferably lieswithin a range of circulating concentrations that include the ED₅₀ withlittle or no toxicity. The dosage can vary within this range dependingupon the dosage form employed, and the route of administration utilized.

[0065] The exact formulation, route of administration, and dosage can bechosen by the individual physician in view of the patient's condition.Dosage amount and interval can be adjusted individually to provideplasma levels of the active moiety which are sufficient to maintain thetherapeutic effects.

[0066] The amount of composition administered is dependent on thesubject being treated, on the subject's weight, the severity of theaffliction, the manner of administration, and the judgment of theprescribing physician.

[0067] Specifically, for administration to a human in the curative orprophylactic treatment of the conditions and disorders identified above,oral dosages of a compound of formula, (I) generally are about 0.5 toabout 1000 mg daily for an average adult patient (70 kg). Thus, for atypical adult patient, individual tablets or capsules contain 0.2 to 500mg of active compound, in a suitable pharmaceutically acceptable vehicleor carrier, for administration in single or multiple doses, once orseveral times per day. Dosages for intravenous, buccal, or sublingualadministration typically are 0.1 to 500 mg per single dose as required.In practice, the physician determines the actual dosing regimen which ismost suitable for an individual patient, and the dosage varies with theage, weight, and response of the particular patient. The above dosagesare exemplary of the average case, but there can be individual instancesin which higher or lower dosages are merited, and such are within thescope of this invention.

[0068] For human use, a compound of the formula (I) can be administeredalone, but generally is administered in admixture with a pharmaceuticalcarrier selected with regard to the intended route of administration andstandard pharmaceutical practice. Pharmaceutical compositions for use inaccordance with the present invention thus can be formulated in aconventional manner using one or more physiologically acceptablecarriers comprising excipients and auxiliaries that facilitateprocessing of compounds of formula (I) into preparations which can beused pharmaceutically.

[0069] These pharmaceutical compositions can be manufactured in aconventional manner, e.g., by conventional mixing, dissolving,granulating, dragee-making, levigating, emulsifying, encapsulating,entrapping, or lyophilizing processes. Proper formulation is dependentupon the route of administration chosen. When a therapeuticallyeffective amount of a compound of the present invention is administeredorally, the composition typically is in the form of a tablet, capsule,powder, solution, or elixir. When administered in tablet form, thecomposition can additionally contain a solid carrier, such as a gelatinor an adjuvant. The tablet, capsule, and powder contain about 5% toabout 95% compound of the present invention, and preferably from about25% to about 90% compound of the present invention. When administered inliquid form, a liquid carrier such as water, petroleum, or oils ofanimal or plant origin can be added. The liquid form of the compositioncan further contain physiological saline solution, dextrose or othersaccharide solutions, or glycols. When administered in liquid form, thecomposition contains about 0.5% to about 90% by weight of a compound ofthe present invention, and preferably about 1% to about 50% of acompound of the present invention.

[0070] When a therapeutically effective amount of a compound of thepresent invention is administered by intravenous, cutaneous, orsubcutaneous injection, the composition is in the form of apyrogen-free, parenterally acceptable aqueous solution. The preparationof such parenterally acceptable solutions, having due regard to pH,isotonicity, stability, and the like, is within the skill in the art. Apreferred composition for intravenous, cutaneous, or subcutaneousinjection typically contains, in addition to a compound of the presentinvention, an isotonic vehicle.

[0071] For oral administration, the compounds can be formulated readilyby combining a compound of formula (I) with pharmaceutically acceptablecarriers well known in the art. Such carriers enable the presentcompounds to be formulated as tablets, pills, dragees, capsules,liquids, gels, syrups, slurries, suspensions and the like, for oralingestion by a patient to be treated. Pharmaceutical preparations fororal use can be obtained by adding a compound of formula (I) with asolid excipient, optionally grinding a resulting mixture, and processingthe mixture of granules, after adding suitable auxiliaries, if desired,to obtain tablets or dragee cores. Suitable excipients include, forexample, fillers and cellulose preparations. If desired, disintegratingagents can be added.

[0072] For administration by inhalation, compounds of the presentinvention are conveniently delivered in the form of an aerosol spraypresentation from pressurized packs or a nebulizer, with the use of asuitable propellant. In the case of a pressurized aerosol, the dosageunit can be determined by providing a valve to deliver a metered amount.Capsules and cartridges, e.g., gelatin, for use in an inhaler orinsufflator can be formulated containing a powder mix of the compoundand a suitable powder base such as lactose or starch.

[0073] The compounds can be formulated for parenteral administration byinjection, e.g., by bolus injection or continuous infusion. Formulationsfor injection can be presented in unit dosage form, e.g., in ampules orin multidose containers, with an added preservative. The compositionscan take such forms as suspensions, solutions or emulsions in oily oraqueous vehicles, and can contain formulatory agents such as suspending,stabilizing, and/or dispersing agents.

[0074] Pharmaceutical formulations for parenteral administration includeaqueous solutions of the active compounds in water-soluble form.Additionally, suspensions of the active compounds can be prepared asappropriate oily injection suspensions. Suitable lipophilic solvents orvehicles include fatty oils or synthetic fatty acid esters. Aqueousinjection suspensions can contain substances which increase theviscosity of the suspension. Optionally, the suspension also can containsuitable stabilizers or agents that increase the solubility of thecompounds and allow for the preparation of highly concentratedsolutions. Alternatively, a present composition can be in powder formfor constitution with a suitable vehicle, e.g., sterile pyrogen-freewater, before use.

[0075] Compounds of the present invention also can be formulated inrectal compositions, such as suppositories or retention enemas, e.g.,containing conventional suppository bases. In addition to theformulations described previously, the compounds also can be formulatedas a depot preparation. Such long-acting formulations can beadministered by implantation (for example, subcutaneously orintramuscularly) or by intramuscular injection. Thus, for example, thecompounds can be formulated with suitable polymeric or hydrophobicmaterials (for example, as an emulsion in an acceptable oil) or ionexchange resins, or as sparingly soluble derivatives, for example, as asparingly soluble salt.

[0076] Many of the compounds of the present invention can be provided assalts with pharmaceutically compatible counterions. Suchpharmaceutically acceptable base addition salts are those salts thatretain the biological effectiveness and properties of the free acids,and that are obtained by reaction with suitable inorganic or organicbases.

[0077] In particular, a compound of formula (I) can be administeredorally, buccally, or sublingually in the form of tablets containingexcipients, such as starch or lactose., or in capsules or ovules, eitheralone or in admixture with excipients, or in the form of elixirs orsuspensions containing flavoring or coloring agents. Such liquidpreparations can be prepared with pharmaceutically acceptable additives,such as suspending agents. A compound also can be injected parenterally,for example, intravenously, intramuscularly, subcutaneously, orintracoronarily. For parenteral administration, the compound is bestused in the form of a sterile aqueous solution which can contain othersubstances, for example, salts or monosaccharides, such as mannitol orglucose, to make the solution isotonic with blood.

[0078] For veterinary use, a compound of formula (I) or a nontoxic saltthereof, is administered as a suitably acceptable formulation inaccordance with normal veterinary practice. The veterinarian can readilydetermine the dosing regimen and route of administration that is mostappropriate for a particular animal.

[0079] Thus, the invention provides in a further aspect a pharmaceuticalcomposition comprising a compound of the formula (I), together with apharmaceutically acceptable diluent or carrier therefor. There isfurther provided by the-present invention a process of preparing apharmaceutical composition comprising a compound of formula (I), whichprocess comprises mixing a compound of formula (I), together with apharmaceutically acceptable diluent or carrier therefor.

[0080] In a particular embodiment, the invention includes apharmaceutical composition for the curative or prophylactic treatment oferectile dysfunction in a male animal, or arousal disorder in a femaleanimal, including humans, comprising a compound of formula (I) or apharmaceutically acceptable salt thereof, together with apharmaceutically acceptable diluent or carrier.

[0081] Compounds of formula (I) can be prepared by any suitable methodknown in the art, or by the following processes which form part of thepresent invention. In the methods below, R⁰, R¹, R², and R³ are asdefined in structural formula (I) above. Generally, compounds ofstructural formula (I) can be prepared according to the followingsynthetic schemes.

[0082] In particular, using an appropriately substituted2-arylethylamine or 2-heteroarylethylamine, a compound of generalstructural formula (I) can be prepared using the methods outlined below.Methods A-C are examples of synthetic routes to thediketopiperazine-tetrahydroisoquinolines anddiketopiperazine-tetrahydroimidazopyridines of formula (I). However,additional synthetic routes exist for the synthesis oftetrahydroisoquinolines. For example, see, M. D. Rozwadowska,Heterocycles, 39, 903 (1994); M. Shamma, Isoquinoline Alkaloinds,Chemistry and Pharmacology, Academis Press: New York (1972); and T.Kametani, The Chemistry of the Isoquinoline Alkaloids, Elsevier,Amsterdam (1969).

[0083] The compounds of general structural formula (III) can beprepared, for example, by the Pictet-Spengler reaction. See, W. Whaleyet al., Org. React, 6, 151-206 (1951); S. M. Hutchins et al., TetrahedonLett., 37, 4865 (1996); R. D. Cox et al., Chem. Rev., 95, 1797 (1995);and A. Yokoyama et al., J. Org. Chem., 64, 611 (1999). A substitutedarylethylamine or heteroarylethylamine ester is reacted with an aldehydeto provide a compound (III). The resulting secondary amine (III) then istreated with either an amino acid or an acid halide under suitableacylation conditions to form an amide-ester. Ring cyclization to form acompound of structural formula (I) is accomplished by an intramolecularamine attack on the ester. Compounds (I) also can be derived from asuitable side chain bearing a leaving group (e.g., compound (IV)) thatreacts with a primary amine.

[0084] Alternatively, a compound (I) can be prepared by first reactingan arylethylamine or heteroarylethylamine with an amino acid undertypical peptide coupling conditions to form an amide (V). Ringcyclization to form a diketopiperazine (VI) is accomplished byintramolecular amine attack on the ester. The resulting piperazine (VI)is subjected to a condensation reaction with an aldehyde under modifiedPictet-Spengler conditions to provide a compound of structural formula(I). For a discussion of the modified Pictet-Spengler reaction, see T.A. Miller et al., Bioorg. Med. Chem. Lett., 8, 1065 (1998); A. Previeroet al., Canadian J. of Chemistry, 46, 3404 (1968); and P. Ducrot et al.,Tet. Lett., 40, 9037 (1999).

[0085] A tetrahydroisoquinoline skeleton also can be constructed usingthe Bischler-Napieralski reaction, which includes a cyclodehydration ofan acylated β-arylethylamine. P₂O₅ or POCl₃ are the most typicalcyclization reagents. See, W. M. Whaley et al., Org. React, VI, 74-150(1951); W. D. F. Meutermans et al., Tetrahedron Lett., 36, 7709 (1995);A. Ishida et al., Chem. Pharm. Bull., 34, 1995 (1986); and A. K. Saxenaet al., Indian J. Chem., 13, 230 (1975). Reduction of the resultingimine (VIII), with NaBH₄, for example, provides a1,2,3,4-tetrahydro-β-carboline (IX).

[0086] A modified method C avoids racemisation because the amine firstis acylated, then converted to the thioamide, for example, withLawesson's reagent. Treatment of the thioamide with an alkyl halide oracyl halide provides an iminium halide (XI). Reduction of the crudeintermediate (XII) with NaBH₄ at reduced temperature stereoselectivelyleads to the tetrahydroisoquinoline (IX).

[0087] In the synthesis of compounds of structural formula (I),protecting compounds and protecting groups, like benzyl chloroformateand trichloroethyl chloroformate, which are well known to personsskilled in the art, can be used. Such protecting groups are disclosed,for example, in T. W. Greene et al. “Protective Groups in OrganicSynthesis, Third Edition,” John Wiley and Sons, Inc., NY, N.Y. (1999).These protecting groups are removed in the final steps of the synthesisunder basic, acidic, or hydrogenolytic conditions which are readilyapparent to those skilled in the art. By employing appropriate startingmaterials, and manipulation and protection of chemical functionalities,synthesis of compounds of structural formula (I) not specifically setforth herein can be accomplished by methods analogous to the schemes setforth above.

[0088] Compounds of formula (I) can be converted to other compounds offormula (I). Thus, for example, when a compound contains a substitutedaromatic ring, it is possible to prepare another suitably substitutedcompound of formula (I). Examples of appropriate interconversionsinclude, but are not limited to, OR^(b) to hydroxy by suitable means(e.g., using an agent such as BBr₃, SnCl₂, or a palladium catalyst, suchas palladium-on-carbon), or amino to substituted amino, such asalkylamine, using standard acylating or sulfonylating conditions.

[0089] Compounds of formula (I) can be prepared by the method above asindividual stereoisomers or as a racemic mixture. Individualstereoisomers of the compounds of the invention can be prepared fromracemates by resolution using methods known in the art for theseparation of racemic mixtures into their constituent stereoisomers, forexample, using HPLC on a chiral column, such as Hypersil naphthyl urea,or using separation of salts of stereoisomers. Compounds of theinvention can be isolated in association with solvent molecules bycrystallization from, or evaporation of, an appropriate solvent.

[0090] The pharmaceutically acceptable acid addition salts of thecompounds of formula (I) that contain a basic center can be prepared ina conventional manner. For example, a solution of the free base can betreated with a suitable acid, either neat or in a suitable solution, andthe resulting salt isolated either by filtration or by evaporation undervacuum of the reaction solvent. Pharmaceutically acceptable baseaddition salts can be obtained in an analogous manner by treating asolution of a compound of formula (I) with a suitable base. Both typesof salt can be formed or interconverted using ion-exchange resintechniques. Thus, according to a further aspect of the invention, amethod for preparing a compound of formula (I) or a salt or solvate(e.g., hydrate) is provided, followed by.(i) salt formation, or (ii)solvate (e.g., hydrate) formation.

[0091] The following abbreviations are used hereafter in theaccompanying examples: rt (room temperature), min (minute), h (hour), g(gram), mmol (millimole), m.p. (melting point), eq (equivalents), L(liter), mL (milliliter), μL (microliters), Et₂O (diethyl ether), CH₂Cl₂(dichloromethane), MeOH (methanol), Et₃N (triethylamine), EtOAc (ethylacetate), AcOH (acetic acid), HCl (hydrochloric acid), MeNH₂(methylamine), TFA (trifluoroacetic acid), IPA (isopropyl alcohol), aq(aqueous), NaCl (sodium chloride), Na₂SOI (sodium sulfate), NaHCO₃(sodium bicarbonate), and THF (tetrahydrofuran).

[0092] The following illustrates specific examples of compounds ofstructural formula (I) and synthetic routes to compounds (I).

PREPARATION OF EXAMPLE 1

[0093] (+−,cis)-4-Benzo[1,3]dioxol-5-yl-7-methyl-3,4,6,7,8a,9-hexahydro-1,3,4a,7-tetraaza-cyclopenta[b]naphthalene-5,8-dioneHydrochloride

[0094] Example 1 was prepared from D-histidine monohydrochloridemonohydrate by the following synthetic scheme. Also see S. M. Hutchinset al., Tet. Letters, 37, 4865-4868 (1996).

[0095] Preparation of D-Histidine Methyl Ester Monohydrochloride(Intermediate 1)

[0096] Thionyl chloride (29.37 g, 18.0 mL, 246.9 mmol) was addeddropwise to a suspension of D-histidine monohydrochloride monohydrate(10.35 g, 49.37 mmol) in anhydrous MeOH (150 mL) at 0° C. under anitrogen blanket. The resulting mixture was slowly warmed to roomtemperature, then stirred for 24 hours. The solvent then was removedunder reduced pressure to provide a white solid. The residue wassuspended in Et₂O, which was collected by filtration. Analysis of theresulting solid by ¹H NMR showed it to be a mixture of starting materialand Intermediate 1. The thionyl chloride treatment was repeated threetimes as described above to yield a white solid (11.74 g, 100%) withless than 10% starting material present: ¹H NMR (300 MHz, CDCl₃): δ 9.07(d, J=1.2 Hz, 1H), 8.7-9.1 (bs, 1H), 7.52 (s, 1H), 4.47 (t, J=7.1 Hz,1H), 3.73 (s, 3H), 3.32-3.29 (m, 2H).

[0097] Preparation of (+/−)-cis-o-carboline (Intermediate 2)

[0098] A suspension of Intermediate 1 (3.24 g, 14.59 mmol) and piperonal(2.63 g, 17.51 mmol) in pyridine (70 mL) was warmed to 100° C., thenstirred for 4 hours under a nitrogen blanket. The resulting orangesolution was cooled to room temperature and concentrated in vacuo. Thecrude product was purified by column chromatography (silica gel, 0-20%MeOH/CH₂Cl₂) to yield 1.72 g (39.2%) of an orange solid: TLC R_(f) (10%MeOH/CH₂Cl₂)=0.39; ¹H NMR (300 MHz, CDCl₃): δ 8.99 (s, 1H), 7.07 (s,1H), 7.03 (s, 2H), 6.09 (s, 2H), 5.71 (s, 1H), 4.70-4.65 (m, 1H), 3.80(s, 3H), 3.36-3.25 (m, 2H) MS (API) m/z 302 (M+H). The trans carbolinewas also eluted from the column, but not in pure form: TLC R_(f) (0.10%MeOH/—CH₂Cl₂)=0.34.

[0099] Preparation of (+/−)-cis-2-chloroacetyl-p-carboline (Intermediate3)

[0100] Chloroacetyl chloride (0.6 mL, 7.4 mmol) was added dropwise to amixture of Intermediate 2 (1.72 g, 5.7 mmol) and Et₃N (1.6 mL, 11.4mmol) in THF (40 mL) and water (5 mL) at 0° C. under a nitrogen blanket.The resulting mixture was warmed to room temperature, then stirred forabout 1 hour. The reaction was quenched with 1N HCl (2 mL), thenconcentrated in vacuo. The crude product was purified by columnchromatography (silica gel, 5-10% MeOH/—CH₂Cl₂) to provide 0.49 g(22.8%) of a light yellow solid: TLC R_(f) (3% EtOAc/CH₂Cl₂)=0.43; MS(API) m/z 378 (M+H)

PREPARATION OF EXAMPLE 1

[0101] A mixture of crude Intermediate 3 (0.49 g, 1.29 mmol), 40% MeNH₂in water (1.10 mL, 6.48 mmol) in THF (20 mL) was heated at 45° C. undera nitrogen blanket for 45 minutes. The reaciton was incomplete. Water (2mL) was added to give a clear two-phase mixture. After an additional 20minutes, the resulting solution was cooled to room temperature, quenchedwith concentrated HCl (4 mL), and concentrated to remove THF. Theresulting slurry was filtered, and the solid was washed forward withwater and acetone. The product was obtained as a white solid (0.16 g,36%) after drying at 45° C. under vacuum: mp 227-230° C.; TLC R_(f) (10%MeOH/CH₂Cl₂)=0.20; ¹H NMR (300 MHz, DMSO-d₆): δ 14.7 (bs, 2H), 8.94 (s,1H), 6.80-6.91 (m, 3H), 6.00 (s, 1H), 5.96 (s, 2H), 4.35 (dd, J=4.3 Hz,J=11.2 Hz, 1H), 4.13 (d, J=17.1 Hz, 1H), 3.97 (d, J=17.6 Hz, 1H), 3.60(bs, 1H), 3.41 (dd, J=4.6 Hz, J=16.4 Hz, 1H), 3.17-3.27 (m, 1H), 2.90(s, 3H); MS (API) m/z 341 (M+H); [α]_(D) ^(25° C.)=no observed rotation(c=L0.15, DMSO). Anal. Calcd for C₁₇H₁₇N₄O₄.HCl.0.4H₂O: C, 53.17; H,4.67; N, 14.59. Found: C, 53.26; H, 4.54; N, 14.52. The relativestereochemistry of the product was confirmed to be the cis isomer by NOEdifference experiments (DMSO-d₆): positive NOE enhancements from theC12a proton at 4.35 ppm to the C₄ proton at 6.00 ppm.

PREPARATION OF EXAMPLE 2

[0102]

[0103] The compound of Example 2 can be prepared in a manner similar toExample 1:

PREPARATION OF EXAMPLE 3

[0104]

[0105] The compound of Example 3 can be prepared by the followingsynthetic sequence.

PREPARATION OF EXAMPLE 4 AND 5

[0106] Examples 4 and 5 can be prepared by the synthetic sequence ofExample 3.

PREPARATION OF EXAMPLE 6

[0107]

[0108] Example 6 can be prepared by the following synthetic sequence.

PREPARATION OF EXAMPLE 7

[0109] Example ? can be prepared by the synthetic sequence of Example 6.

PREPARATION OF EXAMPLE 8

[0110]

[0111] The compound of Example 8 can be prepared by the followingsynthetic sequence.

PREPARATION OF EXAMPLE 9

[0112] Example 9 can be prepared by the synthetic sequence of Example 8.

PREPARATION OF EXAMPLE 10

[0113](6R,11aS)-6-Benzo[1,3]dioxol-5-yl-8,9-dimethoxy-2-methyl-2,3,11,11a-tetrahydro-6H-pyrazino-[[1,2-b]isoquinoline-1,4-dione

[0114] Tetrahydroisoquinoline analog Example 10 was prepared from3-(3,4-dimethoxyphenyl)-L-alanine 1 as depicted in the followingsynthetic scheme. See, A. K. Saxena et al., Indian J. Chem., 13, 230-237(1975).

[0115] Preparation of (S)-2-Amino-3-(3,4-dimethoxyphenyl)propionic AcidMethyl Ester (Intermediate 4)

[0116] Thionyl chloride (3.2 g, 2.0 mL, 26.8 mmol) was added dropwise toa suspension 3-(3,4-dimethoxyphenyl)-L-alanine 1 (2.0 g, 8.9 mmol) inanhydrous MeOH (50 mL) at 0° C. under a nitrogen blanket. The mixturewas slowly warmed to room temperature, then stirred for 72 hours. Thesolvent was removed under reduced pressure to provide a solid. The crudeproduct was taken up in CH₂Cl₂₁ then washed with saturated NaHCO₃ andsaturated NaCl. The organic layer was dried over anhydrous Na₂SO₄,filtered and concentrated to yield a light brown oil (1.97 g, 93%).

[0117] Preparation of2-(1-Benzo[1,3]dioxol-5-yl-methanoyl)amino]-3-(3,4-dimethoxyphenyl)-propionicAcid Methyl Ester (Intermediate 5)

[0118] Piperonyloyl chloride (1.90 g, 2.14 mmol) was added portionwiseto a mixture of crude Intermediate 4 (1.90 g, 7.94 mmol) and Et₂O (2.5mL, 18.3 mmol) in CH₂Cl₂ (40 mL) at 0° C. under a nitrogen blanket. Theresulting mixture was stirred for 4 hours at 0° C., then warmed to roomtemperature. The reaction was diluted with CH₂Cl₂ (50 mL) and was washedwith 0.2 M HCl (2×40 mL), saturated NaHCO₃ (40 mL), and saturated NaCl(40 mL). The solution was dried over anhydrous Na₂SO₄, filtered, andconcentration in vacuo to provide a white solid. The solid was collectedby filtration and washed with 20% EtOAc/hexane to yield 3.69 g (100%) ofIntermediate 5.

[0119] TLC R_(f) (5% MeOH/CH₂Cl₂)=0.57; ¹H NMR (300 MHz, CDCl₃): δ 8.62(d, J=7.7 Hz, 1H), 7.42 (dd, J=1.7 Hz, J=8.13 Hz, 1H), 7.36 (d, J=1.6Hz, 1H), 6.98 (d, J=8.2 Hz, 1H), 6.91 (d, J=1.7 Hz, 1H), 6.77-6.85 (m,2H), 6.09 (s, 2H), 4.58 (m, 1H), 3.69 (s, 6H), 3.64 (s, 3H), 2.95-3.10(m, 2H)

[0120] Preparation of1-Benzo[1,3]dioxol-5-yl-6,7-dimethoxy-3,4,4a,-8a-tetrahydroisoquinoline-3-carboxylicAcid Methyl Ester (Intermediate 6)

[0121] A mixture of Intermediate 5 (3.074 g, 7.94 mmol), and POCl₃ (15mL) was heated at 120° C. under a nitrogen blanket for 1.5:hours. Themixture was cooled to room temperature, then poured onto ice water (100mL) and extracted with EtOAc (2×200 mL). The combined organic layerswere dried over anhydrous Na₂SO₄, filtered, and concentrated to a tanfoam. The crude product was purified by column chromatography on silicagel using 1% Et₃N in 5% MeOH/CH₂Cl₂ to provide Intermediate 6 as a beigefoam (1.60 g, 55%): TLC R_(f) (5% MeOH/CH₂Cl₂)=0.55; ¹H NMR (300 MHz,CDCl₃) δ: 7.17 (d, J=1.6 Hz, 1H), 7.11 (dd, J=8.0 Hz, J=1.6 Hz, 1H),6.85 (m, 2H), 6.79 (s, 1H), 6.01 (d, J=1.1 Hz, 2H), 4.30 (dd, J=12.3 Hz,J=6.3 Hz, 1H), 3.95 (s, 3H), 3.81 (s, 3H), 3.77 (s, 3H), 2.91-3.08 (m,2H); MS (API) m/z 370 (M+H).

[0122] Preparation of1-Benzo[1,3]dioxol-5-yl-6,7-dimethoxy-1,2,3,4,4a,8a-hexahydroisoquinoline-3-carboxylicAcid Methyl Ester (Intermediate 7)

[0123] A solution of Intermediate 6 (1.5 g, 4.06 mmol) in MeOH (60 mL)was cooled to 0° C. and stirred under a nitrogen blanket. Sodiumborohydride (154 mg) was added, and the resulting mixture was stirredfor 2 hours. The reaction mixture then was concentrated in vacuo, duringwhich time a white solid precipitated. The solid was triturated withMeOH (20 mL), collected by filtration, and dried to give 0.82 g (54%) ofIntermediate 7: TLC R_(f) (90:10:1 CH₂Cl₂/EtOAc/MeOH)=0.33; ¹H NMR (300MHz, CDCl) δ: 6.84 (dd, J=7.8 Hz, J=1.6 Hz, 1H), 6.76-6.79 (m, 2H), 6.62(s, 1H), 6.21 (s, 1H), 5.95 (dd, J=3.4 Hz, J=1.1 Hz, 2H), 5.02 (bs 1H),3.82-3.86 (m, 1H), 3.86 (s, 3H), 3.78 (s, 3H) 3.64 (s, 3H), 3.01-3.14(m, 2H), 2.41 (bs, NH); MS (API) m/z 372 (M+H).

[0124] Preparation of1-Benzo[1,3]dioxol-5-yl-2-(2-chloroethanoyl)-6,7-dimethoxy-1,2,3,4,4a,8a-hexahydroisoquinoline-3-carboxylicacid methyl ester (Intermediate 8)

[0125] Chloroacetyl chloride (0.23 mL), 2.88 mmol) was added dropwise toa mixture of Intermediate 7 (0.82 g, 2.21 mmol) and Et₃N (0.71 mL, 5.09mmol) in CH₂Cl₂ (15 mL) at 0° C. under a nitrogen blanket. The resultingmixture was warmed to room temperature and stirred for about 0.5 hour.The reaction was quenched with 1 N HCl (2 mL), and diluted with CH₂Cl₂(50 mL) and-water (10 mL). The layers were separated and the organic waswashed with saturated NaCl and dried over anhydrous Na₂SO₄. Filtrationand concentration in vacuo afforded Intermediate 8 (1.5 g), which wasused without further purification. TLC R_(f) (10% EtOAc/CH₂Cl₂)=0.55; MS(API) m/z 448 (M+H), 472 (M+Na).

PREPARATION OF EXAMPLE 10

[0126] A mixture of crude Intermediate 8 (0.99 g, 2.21 mmol), 40% MeNH₂in water (1.8 mL, 22.2 mmol) in THF (15 mL) was heated at 45° C. under anitrogen blanket for 1.5 hours. The reaction was quenched withconcentrated HCl until the pH was acidic. The mixture was concentratedto remove THF. To the resulting slurry was added 3:1 water:MeOH (30 mL)The solid was collected by filtration, washed with water and Et₃O (2×10mL), and dried to provide Example 10 as a white solid (0.74 g, 82%): mp235-236° C.; TLC R_(f) (10% EtOAc/CH₂Cl₂).=0.14; ¹H NMR (300 MHz,DMSO-d₆) δ: 7.21 (s, 1H), 6.99 (s, 1H), 6.74-6.77 (m, 2H), 6.54 (dd,J=1.2 Hz, J=7.4 Hz, 1H), 6.29 (a, 1H), 5.94 (d, J=6.3 Hz, 2H), 4.17-4.28(m, 2H), 3.93 (d, J=16.5 Hz, 1H), 3.76 (s, 3H), 3.74 (s, 3H), 3.17 (dd,J=3.2 Hz, J=3.9 Hz, 1H), 2.95 (s 3H), 2.72 (dd, J=2.7 Hz, J=12.9 Hz,1H); MS (API) m/z 411 (M+H), 433 (M+Na); [α]_(D) ^(25° C.)=no observedrotation (c=0.43, DMSO). Anal. Calcd for C₂₂H₂₂N₂O₆e0.15H₂O: C, 6.3.96;H, 5.44; N, 6.78. Found: C, 63.88; H, 5.45; N, 6.84. The relativestereochemistry of the product was confirmed to be the trans isomer byNOE difference experiments (DMSO-d₆): no positive NOE enhancements fromthe C6 proton at 3.93 ppm to the C11 proton at 6.29 ppm.

PREPARATION OF EXAMPLE 11

[0127] The compound of Example 11 can be prepared by the syntheticsequence of Example 10.

[0128] Compounds of the present invention can be formulated into tabletsfor oral administration. For example, a compound of formula (I) can beformed into a dispersion with a polymeric carrier by the coprecipitationmethod set forth in WO 96/38131, incorporated herein by reference. Thecoprecipitated dispersion can be blended with excipients, then pressedinto tablets, which optionally are film-coated.

[0129] The compounds of structural-formula (I) were tested for anability to inhibit PDE5. The ability of a compound to inhibit PDE5activity is related to the IC₅₀ value for the compound, i.e., theconcentration of inhibitor required for 50% inhibition of enzymeactivity. The IC₅₀ value for compounds of structural formula (I) weredetermined using recombinant human PDE5.

[0130] The compounds of the present invention typically exhibit an IC₅₀value against recombinant human PDE5 of less than about 50 μM, andpreferably less than about 25 μM, and more preferably less than about 15μm. The compounds of the present invention typically exhibit an IC₅₀value against recombinant human PDE5 of less than about 1 μM, and oftenless than about 0.05 μM. To achieve the full advantage of the presentinvention, a present PDE5 inhibitor has an IC₅₀ of about 0.1 nM to about15 μM.

[0131] The production of recombinant human PDEs and the IC₅₀determinations can be accomplished by well-known methods in the art.Exemplary methods are described as follows:

[0132] Expression of H PDEs

[0133] Expression in Saccharomyces Cerevisiae (Yeast)

[0134] Recombinant production of human PDE1B, PDE2, PDE4A, PDE4B, PDE4C,PDE4D, PDE5, and PDE7 was carried out similarly to that described inExample 7 of U.S. Pat. No. 5,702,936, incorporated herein by reference,except that the yeast transformation vector-employed, which is derivedfrom the basic ADH2 plasmid described in Price et al., Methods inEnzymology, 185, pp. 308-318 (1990), incorporated yeast ADH2 promoterand terminator sequences and the Saccharomyces cerevisiae host was theprotease-deficient strain BJ2-54 deposited on Aug. 31, 1998 with theAmerican Type Culture Collection, Manassas, Va., under accession numberATCC 74465. Transformed host cells were grown in 2×SC-leu medium, pH6.2, with trace metals, and vitamins. After 24 hours, YEPmedium-containing glycerol was added to a final concentration of2×YET/3% glycerol. Approximately 24 hr later, cells were harvested,washed, and stored at −70° C.

[0135] Human Phosphodiesterase Preparations

[0136] Phosphodiesterase Activity Determinations

[0137] Phosphodiesterase activity of the preparations was determined asfollows. PDE assays utilizing a charcoal separation technique wereperformed essentially as described in Loughney et al. (1996). In thisassay, PDE activity converts [32P]cAMP or [32P]cGMP to the corresponding[32P]5′-AMP or [32P]5′-GMP in proportion to the amount of PDE activitypresent. The [32P]5′-AMP or [32P]5′-GMP then was quantitativelyconverted to free [32P]phosphate and unlabeled adenosine or guanosine bythe action of snake venom 5′-nucleotidase. Hence, the amount of[32P]phosphate liberated is proportional to enzyme activity. The assaywas performed at 30° C. in a 100 μL reaction mixture containing (finalconcentrations) 40 μM Tris HCl (pH 8.0), 1 μM ZnSO₄₁ 5 mM MgCl₂, and 0.1mg/mL bovine serum albumin (BSA). PDE enzyme was present in quantitiesthat yield <30% total hydrolysis of substrate (linear assay conditions).The assay was initiated by addition of substrate (1 mM [32P]cAMP orcGMP), and the mixture was incubated for 12 minutes. Seventy-five (75)μg of Crotalus atrox venom then was added, and the incubation wascontinued for 3 minutes (15 minutes total). The reaction was stopped byaddition of 200 μL of activated charcoal (25 mg/mL suspension in 0.1 MNaH₂PO₄, pH 4). After centrifugation (750×g for 3 minutes) to sedimentthe charcoal, a sample of the supernatant was taken for radioactivitydetermination in a scintillation counter and the PDE activity wascalculated.

[0138] Purification of PDE5 from S. cerevisiae

[0139] Cell pellets (29 g) were thawed on ice with an equal volume ofLysis Buffer (25 mM Tris HCl, pH 8, 5 mM MgCl₂, 0.25 mM DTT, 1 mMbenzamidine, and 10 μM ZnSO₄). Cells-were lysed in a Microfluidizer®(Microfluidics Corp.) using nitrogen at 20,000 psi. The lysate wascentrifuged and filtered through 0.45 μm disposable filters. Thefiltrate was applied to a 150 mL column of Q SEPHAROSE® Fast-Flow(Pharmacia). The column was washed with 1.5 volumes of Buffer A (20 nMBis-Tris Propane, pH 6.8, 1 mM MgCl₂, 0.25 mM DTT, 10 μM ZnSO₄) andeluted with a step gradient of 125 mM NaCl in Buffer A followed by alinear gradient of 125-1000 mM NaCl in Buffer A. Active fractions fromthe linear gradient were applied to a 180 mL hydroxyapatite column inBuffer B (20 mM Bis-Tris Propane (pH 6.8), 1 mM MgCl₂, 0.25 mM DTT, 10μM ZnS₄O, and 0.250 mM KCl). After loading, the column was washed with 2volumes of Buffer B and eluted with a linear gradient of 0-125 mMpotassium phosphate in Buffer B. Active fractions were pooled,precipitated with 60% ammonium sulfate, and resuspended in Buffer C (20mM Bis-Tris Propane, pH 6.8, 125 mM NaCl, 0.5 mM DTT, and 10 μM ZnSO₄).The pool was applied to/a 140 mL column of SEPHACRYL® S-300 HR andeluted with Buffer C. Active fractions were diluted to 50% glycerol andstored at −20° C.

[0140] The resultant preparations were about 85% pure by SDS-PAGE. Thesepreparations had specific activities of about 3 mmol cGMP hydrolyzed perminute per milligram protein.

[0141] Inhibitory Effect on cGMP-PDE

[0142] cGMP-PDE activity of compounds of the present invention wasmeasured using a one-step assay adapted from Wells et al., Biochim.Biophys. Acta, 384, 430 (1975). The reaction medium contained 50 mMTris-HCl, pH 7.5, 5 mM magnesium acetate, 250 μg/ml 5′-Nucleotidase, 1mM EGTA, and 0.15 μM 8-[H³]-cGMP. Unless otherwise indicated, the enzymeused was a human recombinant PDE5 (ICOS Corp., Bothell, Wash.).

[0143] Compounds of the invention were dissolved in DMSO finally presentat 2% in the assay. The incubation time was 30 minutes-during which thetotal substrate conversion did not exceed 30%.

[0144] The IC₅₀ values for the compounds examined were determined fromconcentration-response curves typically using concentrations rangingfrom 10 nM to 10 μM. Tests against other PDE enzymes using standardmethodology showed that compounds of the invention are selective for thecGMP-specific PDE enzyme.

[0145] Biological Data

[0146] The compounds according to the present invention were typicallyfound to exhibit an IC₅₀ value of less than 1000 nM. An in vitro testdata for representative compounds of the invention is given in thefollowing table: TABLE 1 IN vitro results Example PDE5 IC₅₀ (nM) 1 324010 718

[0147] Obviously, many modifications and variations of the invention ashereinbefore set forth can be made without departing from the spirit andscope thereof, and, therefore, only such limitations should be imposedas are indicated by the appended claims.

What is claimed is:
 1. A compound having a formula

wherein R⁰, independently, is selected from the group consisting ofhalo, C₁₋₆alkyl; C₂₋₆alkenyl, aryl, heteroaryl, C₃₋₈cycloalkyl,C₃₋₈heterocycloalkyl, C₁₋₃alkylenearyl, C₁₋₃alkyleneheteroaryl, Het,C(═O)R^(a), OC(═O)OR^(a), C₁₋₄alkyleneNR^(a)R^(b), C₁₋₄alkyleneHet,C₁₋₄alkyleneC(═O)OR^(a), C(═O)NR^(a)SO₂R^(b), C(═O)C₁₋₄alkyleneHet,C(═O)NR^(a)R^(b), C(═O)NR^(a)C₁₋₄alkyleneOR^(b),C(═O)NR^(a)C₁₋₄alkyleneHet, OR^(a), OC₁₋₄alkyleneC(═O)OR^(a),OC₁₋₄alkyleneNR^(a)R^(b), OC₁₋₄alkyleneHet, OC₁₋₄alkyleneOR^(a),OC₁₋₄alkyleneNR^(a)C(═O)OR^(b), NR^(a)R^(b),NR^(a)C₁₋₄alkyleneNR^(a)R^(b), NR^(a)C(═O)R^(b), NR^(a)C(═O)NR^(a)R^(b),N(SO₂C₁₋₄alkyl)₂, NR^(a)(SO₂C₁₋₄alkyl), nitro, trifluoromethyl,trifluoromethoxy, cyano, SO₂NR^(a)R^(b), SO₂R^(a), SOR^(a), SR^(a), andOSO₂CF₃; R¹ is selected from the group consisting of hydrogen,C₁₋₆alkyl, C₂₋₆alkenyl, C₂₋₆alkynyl, haloC₁₋₆alkyl, C₃₋₈cycloalkyl,C₃₋₈cycloalkylC₁₋₃alkyl, arylC₁₋₃alkyl, and heteroarylC₁₋₃alkyl; R² isselected from the group consisting of an optionally substitutedmonocyclic aromatic ring selected from the group consisting of benzene,thiophene, furan, and pyridine, and an optionally substituted bicyclicring

wherein the fused ring A is a 5- or 6-membered ring, saturated orpartially or fully unsaturated, and comprises carbon atoms andoptionally one or two heteroatoms selected from oxygen, sulfur, andnitrogen; R³ is hydrogen or C₁₋₆alkyl, or R¹ and R³ together form a 3-or 4-membered alkyl or alkenyl chain component of a 5- or 6-memberedring; fused ring B is a 5-, 6-, or 7-membered ring, saturated orpartially or fully unsaturated, comprising carbon atoms and optionallyone to three heteroatoms selected from oxygen, sulfur, and nitrogen;R^(a) is selected from the group consisting of hydrogen, C₁₋₁₀alkyl,C₂₋₁₀alkenyl, C₂₋₁₀alkynyl, aryl, heteroaryl, arylC₁₋₃alkyl,C₁₋₃alkylenearyl, C(═O)OR^(b), C(═O)N(R^(b))₂, C₁₋₄alkyleneN(R^(b))₂,CF₃, OCF₃, OR^(b), OC(═O)R^(b), OC₁₋₄alkyleneC(═O)OR^(b),C₁₋₄alkyleneOC₁₋₄alkyleneC(═O)OR^(b), C(═O)NR^(b)SO₂R^(b),C(═O)C₁₋₄alkyleneHet, C₂₋₆alkenyleneN(R^(b))₂,C(═O)NR^(b)C₁₋₄alkyleneOR^(b), C(═O)NR^(b)C₁₋₄alkyleneHet,OC₂₋₄alkyleneN(R^(b))₂, C₁₋₄alkyleneCH(OR^(b)) CH₂N(R^(b))₂,OC₂₋₄alkyleneOR^(b), OC₂₋₄alkyleneNR^(b)C(═O)OR^(b), N(R^(b))₂,NR^(b)C₁₋₄alkyleneN(R^(b))₂, NR^(b)C(═O)R^(b), NR^(b)C(═O)N(R^(b))₂,N(SO₂C₁₋₄alkyl)₂, NR^(b)(SO₂C₁₋₄alkyl) SO₂N(R^(b))₂,OSO₂trifluoromethyl, C(═O)R^(b), C₁₋₃alkyleneOR^(b), CN, andC₁₋₆alkyleneC(═O)OR^(b); R^(b) is selected from the group consisting ofhydrogen, C₁₋₆alkyl, aryl, arylC₁₋₃alkyl, C₁₋₃alkylenearyl, heteroaryl,heteroarylC₁₋₃alkyl, and C₁₋₃alkyleneheteroaryl; q is 0, 1, 2, 3, or 4;and pharmaceutically acceptable salts and hydrates thereof.
 2. Thecompound of claim 1 represented by the formula

and pharmaceutically acceptable salts and solvates thereof.
 3. Thecompound of claim 1 wherein q is
 0. 4. The compound of claim 1 whereinR⁰ is selected from the group consisting of C₁₋₆alkyl, aryl,C₁₋₃alkylenearyl, C₁₋₃alkyleneheteroaryl, Het, OR^(a), C(═O)OR^(a),C₁₋₄alkyleneNR^(a)R^(b), C(═O)R^(a), NR^(a)R^(b), C₃₋₈cycloalkyl, andC(═O)NR^(a)R^(b).
 5. The compound of claim 1 wherein R¹ is selected fromthe group consisting of hydrogen, C₁₋₆alkyl, haloC₁₋₆alkyl,C₃₋₈cycloalkyl, C₃₋₈cycloalkyleneC₁₋₃alkyl, arylC₂₋₃alkyl, andheteroarylC₁₋₃alkyl.
 6. The compound of claim 1 wherein R² is anoptionally substituted bicyclic ring selected from the group consistingof naphthalene, indene, benzoxazole, benzothiazole, benzisoxazole,benzimidazole, quinoline, indole, benzothiophene, and benzofuran.
 7. Thecompound of claim 1 wherein R² is

and wherein q is an integer 1 or 2, and G, independently, are C(R^(a))₂,O, S, or NR^(a).
 8. The compound of claim 1 wherein R², optionallysubstituted, is selected from the group consisting of


9. The compound of claim 1 wherein the B ring is selected from the groupconsisting of cyclopentyl, cyclohexyl, cycloheptyl, cyclopentenyl,cyclohexenyl, 1,3,5-cyclohepatrienyl, phenyl, furanyl, thienyl,2H-pyrrolyl, pyrrolyl, 2-pyrrolinyl, 3-pyrrolinyl, pyrrolidinyl,1,3-dioxolanyl, oxazolyl, thiazolyl, imidazolyl, 2-imidazolinyl,imidazolidinyl, pyrazolyl, 2-pyrazolinyl, pyrazolidinyl, isoxazolyl,isothiazolyl, 1,2,3-oxadiazolyl, 1,2,3-triazolyl, 1,3,4-thiadizolyl,3H-pyrrolyl, 1,2-dithiolyl, 1,3-dithiolyl, 3H-1,2-oxathiolyl,1,2,4-oxadiazolyl, 1,2,5-oxadiazolyl, 1,3,4-oxadiazolyl,1,2,3,4-oxatriazolyl, 1,2,3,5-oxatriazolyl, 3H-1,2,3-dioxazolyl,1,2,4-dioxazole, 1,3,2-dioxazole, 1,3,4-dioxazolyl,5H-1,2,5-oxathiazolyl, 1,3-oxathiolyl, 2H-pyranyl, 4H-pyranyl,pyridinyl, piperidinyl, 1,4-dioxanyl, morpholinyl, 1,4-dithianyl,thiomorpholinyl, pyridazinyl, pyrimidinyl, pyrazinyl, piperazinyl,1,3,5-triazinyl, 1,3,5-trithanyl, 2-pyrronyl, 4-pyronyl, 1,2-dioxinyl,1,3-dioxinyl, 1,2,4-triazinyl, 1,2,3-triazinyl, 4H-1,3-oxadinyl,2H-1,3-oxazinyl, 6H-1,3-oxazinyl, 6H-1,2-oxazinyl, 2H-1,2-oxazinyl,4H-1,4-oxazinyl, 1,2,5-oxathiazinyl, 1,4-oxazinyl, o-isoxazinyl,p-isoxazinyl, 1,2,5-oxathiazinyl, 1,2,6-oxathiazinyl, 1,4,2-oxadiazinyl,1,3,5,2-oxadiazinyl, azepinyl, oxepinyl, thiepinyl, 1,2,4-diazepinyl,and residues thereof.
 10. The compound of claim 9 wherein the B ring,unsubstituted or substituted, is selected from the group consisting ofphenyl, imidazolyl, pyrrolyl, thienyl, furanyl, thiazolyl, oxazolyl,piperidinyl, cyclohexyl, pyrimidinyl, triazinyl, piperazinyl, andimidazolinyl.
 11. A compound selected from the group consisting of

and pharmaceutically acceptable salts and solvates thereof.
 12. Apharmaceutical composition comprising a compound of claim 1, togetherwith a pharmaceutically acceptable diluent or carrier.
 13. A method oftreating a male or female animal for a condition where inhibition of acGMP-specific PDE is of a therapeutic benefit comprising administeringto said animal an effective amount of a pharmaceutical compositioncomprising a compound of claim 1, together with a pharmaceuticallyacceptable diluent or carrier.
 14. The method of claim 13 wherein thecondition is male erectile dysfunction.
 15. The method of claim 14wherein the treatment is an oral treatment.
 16. The method of claim 13wherein the condition is female arousal disorder.
 17. The method ofclaim 16 wherein the treatment is an oral treatment.
 18. The method ofclaim 13 wherein the condition is selected from the group consisting ofstable angina, unstable angina, variant angina, hypertension, pulmonaryhypertension, chronic obstructive pulmonary disease, malignanthypertension, pheochromocytoma, acute respiratory distress syndrome,congestive heart failure, acute renal failure, chronic renal failure,atherosclerosis, a condition of reduced blood vessel patency, aperipheral vascular disease, a vascular disorder, thrombocythemia, aninflammatory disease, myocardial infarction, stroke, bronchitis, chronicasthma, allergic asthma, allergic rhinitis, glaucoma, peptic ulcer, agut motility disorder, postpercutaneous transluminal coronaryangioplasty, carotid angioplasty, post-bypass surgery graft stenosis,osteoporosis, preterm labor, benign prostatic hypertrophy, and irritablebowel syndrome.
 19. A method of treating a condition where inhibition ofa cGMP-specific PDE is of therapeutic benefit, in a human or a nonhumananimal body, comprising administering to said body a therapeuticallyeffective amount of a compound of claim
 1. 20. A method for the curativeor prophylactic treatment of male erectile dysfunction or female arousaldisorder, comprising administration of an effective dose of a compoundof claim 1, and pharmaceutically acceptable salts and solvates thereof,to an animal.
 21. Use of a compound of claim 1 for the manufacture of amedicament for the curative or prophylactic treatment of a conditionwhere inhibition of a cGMP-specific PDE is of a therapeutic benefit.